RESUMO
Four long-chain, linear fatty acid dopamides (N-acyldopamines) have been identified in nervous bovine and rat tissues. Two unsaturated members of this family of lipids, N-arachidonoyl-dopamine (NADA) and N-oleoyl-dopamine, were shown to potently activate the transient receptor potential channel type V1 (TRPV1), also known as the vanilloid receptor type 1 for capsaicin. However, the other two congeners, N-palmitoyl- and N-stearoyl-dopamine (PALDA and STEARDA), are inactive on TRPV1. We have investigated here the possibility that the two compounds act by enhancing the effect of NADA on TRPV1 ('entourage' effect). When pre-incubated for 5 min with cells, both compounds dose-dependently enhanced NADA's TRPV1-mediated effect on intracellular Ca(2+) in human embryonic kidney cells overexpressing the human TRPV1. In the presence of either PALDA or STEARDA (0.1-10 microm), the EC(50) of NADA was lowered from approximately 90 to approximately 30 nm. The effect on intracellular Ca(2+) by another endovanilloid, N-arachidonoyl-ethanolamine (anandamide, 50 nm), was also enhanced dose-dependently by both PALDA and STEARDA. PALDA and STEARDA also acted in synergy with low pH (6.0-6.7) to enhance intracellular Ca(2+) via TRPV1. When co-injected with NADA (0.5 micrograms) in rat hind paws, STEARDA (5 micrograms) potentiated NADA's TRPV1-mediated nociceptive effect by significantly shortening the withdrawal latencies from a radiant heat source. STEARDA (1 and 10 micrograms) also enhanced the nocifensive behavior induced by carrageenan in a typical test of inflammatory pain. These data indicate that, despite their inactivity per se on TRPV1, PALDA and STEARDA may play a role as 'entourage' compounds on chemicophysical agents that interact with these receptors, with possible implications in inflammatory and neuropathic pain.
Assuntos
Dopamina/análogos & derivados , Dopamina/farmacologia , Receptores de Droga/efeitos dos fármacos , Animais , Ácidos Araquidônicos/farmacologia , Cálcio/metabolismo , Carragenina/efeitos adversos , Linhagem Celular , Modelos Animais de Doenças , Dopamina/biossíntese , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos/métodos , Sinergismo Farmacológico , Quimioterapia Combinada , Endocanabinoides , Membro Posterior , Humanos , Hiperalgesia/induzido quimicamente , Hiperalgesia/complicações , Hiperalgesia/tratamento farmacológico , Inflamação/induzido quimicamente , Inflamação/complicações , Inflamação/tratamento farmacológico , Itália , Rim/embriologia , Rim/patologia , Masculino , Medição da Dor/métodos , Palmitatos/farmacologia , Alcamidas Poli-Insaturadas , Ratos , Ratos Sprague-Dawley , Receptores de Droga/genética , Estearatos/farmacologia , Canais de Cátion TRPVRESUMO
In this issue of Cell Stem Cell, Biernaskie et al. (2009) demonstrate that a specific subpopulation of dermal papilla fibroblasts, marked by Sox2 expression, displays properties of adult stem cells, including serial hair follicle initiation, dermal cell differentiation, and skin-derived precursor production.
RESUMO
In addition to protecting epithelial cells from mechanical stress, keratins regulate cytoarchitecture, cell growth, proliferation, apoptosis, and organelle transport. In this issue, Vijayaraj et al. (2009. J. Cell Biol. doi:10.1083/jcb.200906094) expand our understanding of how keratin proteins participate in the regulation of protein synthesis through their analysis of mice lacking the entire type II keratin gene cluster.